Sorry for not posting this yesterday, my family took a day trip to NASA and I forgot about this.
Monster
It took twenty years for every cell in your body to be replaced. Phantom knew that.
A few times the clock would painfully reset, the human seperated from his soul. Every time he would fuse with Danny again, each time more painful for him then the last.
His time was almost up. Danny only had a few cells infused with the original ectoplasm left. He must have felt it, because he tried to use his powers less and less as the years went by.
And who wouldn't feel a monster itching in your skin?